<a>

Resum

L'element HTML <a> (de l'Anglès Anchor) defineix un hipervincle, el name target de la destinació per un hipervincle, o ambdós.

• Categories de contingut Contingut de flux, phrasing content, contingut interactiu, contingut palpable.
• Contingut permès Transparent, conté o contingut de flux o  phrasing content .
• Omissió de l'etiqueta Cap, tant l'etiqueta inicial com l’etiqueta final són obligatòries
• Elements pares permesos Qualsevol element que accepti phrasing content, o qualsevol element que accepti contingut de flux.
• Interfície DOM HTMLAnchorElement

Atributs

Aquest element inclou els atributs globals.

download HTML5

Aquest atribut, en cas que hi sigui present, indica que l'autor pretén que l'hipervincle sigui usat per descarregar un recurs de forma que quan l'usuari cliqui en l'enllaç se'ls demanarà que de guardar-ho com un arxiu local. Si l'atribut té un valor, el valor s'utilitza com el nom del fitxer precarregada al Save prompt que s'obre quan l'usuari fa clic a l'enllaç (l'usuari pot canviar el nom abans de guardar-és clar). No hi ha restriccions en valors permesos (though / and \ will be converted to underscores, preventing specific path hints), però s'hauria de considerar que la majoria dels sistemes de fitxers tenen limitacions amb regard to what punctuation is supported en noms d'arxius, i els navegadors are likely to adjust file names accordingly.

Nota:

• Can be used with blob: URLs i data: URLs, per fer més més fàcil pels usuaris per descarregar contingut que és generat  to download content that is generated programmatically using JavaScript (e.g. a picture created using an online drawing Web app).
• If the HTTP header Content-Disposition: is present and gives a different filename than this attribute, the HTTP header has priority over this attribute.
• If this attribute is present and Content-Disposition: is set to inline, Firefox gives priority to Content-Disposition, like for the filename case, while Chrome gives priority to the download attribute.
• En Firefox 20 aquest atribut només s'honra pels enllaços als recursos amb el mateix origen.

href

This was the single required attribute for anchors defining a hypertext source link, but is no longer required in HTML5. Omitting this attribute creates a placeholder link. The href attribute indicates the link target, either a URL or a URL fragment. A URL fragment is a name preceded by a hash mark (#), which specifies an internal target location (an ID) within the current document. URLs are not restricted to Web (HTTP)-based documents. URLs might use any protocol supported by the browser. For example, file, ftp, and mailto work in most user agents.

Note: You can use the special fragment "top" to create a link back to the top of the page; for example <a href="#top">Return to top</a>. This behavior is specified by HTML5.

media HTML5

This attribute specifies the media which the linked resource applies to. Its value must be a media query. This attribute is mainly useful when linking to external stylesheets by allowing the user agent to pick the best adapted one for the device it runs on.

Usage note:

• In HTML 4, only simple white-space-separated list of media description literals, i.e. media types and groups, where defined and allowed as values for this attribute, like print, screen, aural, braille, ... HTML 5 extended this to any kind of media queries, which are a superset of the allowed values of HTML 4.
• Browsers not supporting the CSS3 Media Queries won't necessarily recognize the adequate link; do not forget to set fallback links, the restricted set of media queries defined in HTML 4.

ping HTML5

The 'ping' attribute, if present, sends the URLs of the resources a notification/ping if the user follows the hyperlink.

rel

For anchors containing the href attribute, this attribute specifies the relationship of the target object to the link object. The value is a comma-separated list of link types values. The values and their semantics will be registered by some authority that might have meaning to the document author. The default relationship, if no other is given, is void. Use this attribute only if the href attribute is present.

target

This attribute specifies where to display the linked resource. In HTML4, this is the name of, or a keyword for, a frame. In HTML5, it is a name of, or keyword for, a browsing context (for example, tab, window, or inline frame). The following keywords have special meanings:

• _self: Load the response into the same HTML4 frame (or HTML5 browsing context) as the current one. This value is the default if the attribute is not specified.
• _blank: Load the response into a new unnamed HTML4 window or HTML5 browsing context.
• _parent: Load the response into the HTML4 frameset parent of the current frame or HTML5 parent browsing context of the current one. If there is no parent, this option behaves the same way as _self.
• _top: In HTML4: Load the response into the full, original window, canceling all other frames. In HTML5: Load the response into the top-level browsing context (that is, the browsing context that is an ancestor of the current one, and has no parent). If there is no parent, this option behaves the same way as _self.

Use this attribute only if the href attribute is present.

charset Obsolete since HTML5

This attribute defines the character encoding of the linked resource. The value is a space- and/or comma-delimited list of character sets as defined in RFC 2045. The default value is ISO-8859-1.

Usage note: This attribute is obsolete in HTML5 and should not be used by authors. To achieve its effect, use the HTTP Content-Type header on the linked resource.

coords HTML 4 only, Obsolete since HTML5

For use with object shapes, this attribute uses a comma-separated list of numbers to define the coordinates of the object on the page.

datafld

This attribute specifies the column name from that data source object that supplies the bound data.

Usage note: This attribute is non-standard and should not be used by authors. To achieve its effect, use scripting and a mechanism such as XMLHttpRequest to populate the page dynamically

Support	Gecko	Presto	WebKit	Trident
	Not implemented	Not implemented	Not implemented	IE4, IE5, IE6, IE7 (Removed in IE8)
Normative document	Microsoft's Data Binding: dataFld Property (MSDN)

datasrc

This attribute indicates the ID of the data source object that supplies the data that is bound to this element.

Usage note: This attribute is non-standard and should not be used by authors. To achieve its effect, use scripting and a mechanism such as XMLHttpRequest to populate the page dynamically.

Support	Gecko	Presto	WebKit	Trident
	Not implemented	Not implemented	Not implemented	IE4, IE5, IE6, IE7 (Removed in IE8)
Normative document	Microsoft's Data Binding: dataSrc Property (MSDN)

hreflang

This attribute indicates the language of the linked resource. It is purely advisory. Allowed values are determined by BCP47 for HTML5 and by RFC1766 for HTML4. Use this attribute only if the href attribute is present.

methods

The value of this attribute provides information about the functions that might be performed on an object. The values generally are given by the HTTP protocol when it is used, but it might (for similar reasons as for the title attribute) be useful to include advisory information in advance in the link. For example, the browser might choose a different rendering of a link as a function of the methods specified; something that is searchable might get a different icon, or an outside link might render with an indication of leaving the current site. This attribute is not well understood nor supported, even by the defining browser, Internet Explorer 4. Methods Property (MSDN)

name HTML 4 only, Obsolete since HTML5

This attribute is required in an anchor defining a target location within a page. A value for name is similar to a value for the id core attribute and should be an alphanumeric identifier unique to the document. Under the HTML 4.01 specification, id and name both can be used with the <a> element as long as they have identical values.

Usage note: This attribute is obsolete in HTML5, use global attribute id instead.

rev HTML 4 only, Obsolete since HTML5

This attribute specifies a reverse link, the inverse relationship of the rel attribute. It is useful for indicating where an object came from, such as the author of a document.

shape HTML 4 only, Obsolete since HTML5

This attribute is used to define a selectable region for hypertext source links associated with a figure to create an image map. The values for the attribute are circle, default, polygon, and rect. The format of the coords attribute depends on the value of shape. For circle, the value is x,y,r where x and y are the pixel coordinates for the center of the circle and r is the radius value in pixels. For rect, the coords attribute should be x,y,w,h. The x,y values define the upper-left-hand corner of the rectangle, while w and h define the width and height respectively. A value of polygon for shape requires x1,y1,x2,y2,... values for coords. Each of the x,y pairs defines a point in the polygon, with successive points being joined by straight lines and the last point joined to the first. The value default for shape requires that the entire enclosed area, typically an image, be used.

Note: It is advisable to use the usemap attribute for the <img> element and the associated <map> element to define hotspots instead of the shape attribute.

type

This attribute specifies the media type in the form of a MIME type for the link target. Generally, this is provided strictly as advisory information; however, in the future a browser might add a small icon for multimedia types. For example, a browser might add a small speaker icon when type is set to audio/wav. For a complete list of recognized MIME types, see https://www.w3.org/TR/html4/references.html#ref-MIMETYPES. Use this attribute only if the href attribute is present.

urn

This supposedly Microsoft-supported attribute relates a uniform resource name (URN) with the link. While it is based on standards work years back, the meaning of URNs is still not well defined, so this attribute is meaningless. urn Property (MSDN)

Example: Linking to an external location

<!-- anchor linking to external file -->
<a href="https://www.mozilla.com/">
External Link
</a>

Result

External Link

Example: Creating a clickable image

This small example use an image to link to the MDN home page. The home page will open in a new browsing context, that is a new page or a new tab.

<a href="https://developer.mozilla.org/en-US/" target="_blank">
  <img src="https://mdn.mozillademos.org/files/6851/mdn_logo.png" alt="MDN logo" />
</a>

Result

Example: Crear un enllaç d'email

És habitual crear botons o enllaços que obriran el programa d'email de l'usuari per permetrels enviar un missatge nou. Això s'aconsegueix fent servir l'enllaç mailto. Aquí hi ha un exemple simple:

<a href="mailto:[email protected]">Send email to nowhere</a>

This results in a link that looks like this: Send email to nowhere.

Per més informació sobre el mailto URL scheme, comaracoom incloure el subjecte, el cos o altre contingut predeterminat, veure  Enllaços d'email o RFC 6068.

Exemple: Fer servir l'atribut de descàrrega per guardar un canvas com a PNG

If you want to allow a user to download an HTML Canvas as an image you can create a link with a download attribute and the canvas data as a file URL:

var link = document.createElement('a');
link.innerHTML = 'download image';
link.addEventListener('click', function(ev) {
    link.href = canvas.toDataURL();
    link.download = "mypainting.png";
}, false);
document.body.appendChild(link);

Pots veure això en acció https://jsfiddle.net/codepo8/V6ufG/2/

Especificacions

Compatibilitat amb navegadors

Clicking and focus

Whether clicking on an <a> causes it to (by default) become focused varies by browser and OS.

Notes

The following are reserved browser key bindings for the two major browsers and should not be used as values to accesskey: a, c, e, f, g, h, v, left arrow, and right arrow.

HTML 3.2 defineix només name, href, rel, rev, i title.

L'atribut target no està definit en navegadors que no suporten frames, com ara la generació de navegadors Netscape 1. Furthermore, target is not allowed under strict variants of XHTML but is limited to frameset or transitional forms.

Recomanacions per JavaScript

It is often the case that an anchor tag is used with the onclick event. In order to prevent the page from refreshing, href is often set to either "#" or "javascript:void(0)". Both of these values can lead to some unexpected errors when copying links and opening links in a new tab and/or window. Be aware of this for usability reasons, and when users do use anchor tags and you prevent default behavior.

Vegeu també

• Altres elements pertanyents a text-level semantics: <abbr>, <em>, <strong>, <small>, <cite>, <q>, <dfn>, <time>, <code>, <var>, <samp>, <kbd>, <sub>, <sup>, <b>, <i>, <mark>, <ruby>, <rp>, <rt>, <bdo>, <span>, <br>, <wbr>.